Quick Answer

Add a reef strontium supplement only if your test kit shows strontium below 8 mg/L. Seachem Reef Strontium is a concentrated option that helps maintain natural seawater levels.

Why Strontium Matters for Corals

Strontium is chemically similar to calcium and occurs in natural seawater at about 8 to 10 mg/L. Many corals and coralline algae incorporate strontium into their skeletons alongside calcium, so maintaining that range supports healthy growth.

In a closed reef tank, strontium can be depleted by coral growth, water changes with synthetic salt, and protein skimming. Regular testing helps you know when levels drop below the natural range.

The Risk of Guessing

Adding strontium without testing can push levels too high, which may interfere with calcium uptake. That's why the first step is always a reliable strontium test kit.

If you already dose calcium and alkalinity, check strontium as part of your routine. Many reefers find strontium drops alongside calcium, so a balanced additive approach works best.

Diagnosis: When to Add Strontium

  • Symptom: Slow coral growth, pale coralline algae, or no visible skeleton extension despite adequate calcium and alkalinity.
  • Likely Cause: Strontium level below 8 mg/L, often from heavy coral growth or infrequent water changes. Test strontium with a reliable kit before dosing.
  • Corrective Action: Dose Seachem Reef Strontium according to the label to raise strontium toward 8–10 mg/L. Retest after 24 hours and adjust gradually. Track doses in a log to avoid overshooting.
  • Stop or Choose Another Option: If your strontium test reads normal (8–10 mg/L), do not dose. If you have a mixed reef with stony corals, consider a comprehensive additive that includes strontium, but if you only keep soft corals, a separate strontium supplement may be unnecessary. When in doubt, skip the dose and rely on regular water changes.

Product Facts

  • Seachem Reef Strontium: Seachem Reef Strontium restores and maintains strontium to levels found in natural seawater using strontium gluconate at 10,000 mg/L. The concentrated formula lets you raise strontium with a small dose, and the gluconate form is readily usable by corals and coralline algae.

    Seachem Reef Strontium

    Seachem Reef Strontium